多尺度天气分析理论和应用Ⅱ:锋面和气旋的形成机制  

Multi-Scale Wather Analysis Theory and Application Ⅱ: Front and Cyclone Formation Mechanisms

作　　者：叶更新 

机构地区：[1]吉林省通化市气象台,吉林通化134001

出　　处：《高原气象》2013年第4期973-982,共10页Plateau Meteorology

基　　金：吉林省气象局科技创新基金项目"地球大气的粒子模型及其在短期气候预测中的应用"(200707)

摘　　要：利用多尺度天气分析理论,研究了锋面和气旋的形成机制。结果表明,冷、暖气团是由不同性质的亚微团在环境力的作用下向不同方向运动而形成的,而它们的交界面就是锋面。急流附近强动能梯度力能促进微团的分离,因此锋面与急流有很好的对应关系。另外,低空急流附近存在上干冷下暖湿的稳定气流,原因在于急流之上的能量梯度力与重力的方向相反,导致该区域微团所受到的作用力为零,形成稳定的结构。但当微团运动到急流出口处时,这种平衡不再存在,暖湿微团向上运动而干冷微团向下运动,形成剧烈的天气变化。地球自转所形成的离心力使得轻微团产生向北、向上的运动分量,导致极锋向北倾斜。气旋的形成同样是由亚微团的分离而产生的。当轻微团离开微团,在绝对环境涡度场的作用下将发生旋转,旋转的方向与初始涡度的方向一致,在北半球地转涡度的垂直分量向上,为逆时针旋转,南半球为顺时针旋转。在气旋的形成过程中,轻亚微团在气压梯度力场和绝对涡度力的作用下呈现螺旋运动,是气旋系统普遍存在螺旋云带和雨带的原因。水汽是气旋在形成和加强过程中的基本能源,由于发生地的不同,温带气旋和台风在水汽输送方式上亦有差别:温带气旋主要依靠低空暖输送带进行水汽输送;台风因为发生在热带海洋,水汽充沛,各个层次都有水汽供应。气旋运动主要受三个力的制约:环境气压梯度场力、绝对涡度场力和环境涡度力,这三个力的作用导致台风在沿副热带高压边缘运动的同时,还存在蛇形路径和打转运动。Using the multi-scale weather analysis theory,the front and cyclone formation mechanisms have been studied.It is found that the warm and cold air mass formations are due to the different kinds of sub-micelles moving in the different directions in effect of the environmental force,and their interface is the front.The kinetic energy gradient force force in the vicinity jet stream can promote the separation of sub-micelles from a micelle,so there is a good correlation between the front and the jet.There is the stable structure that the warm and humid air under dry and cold air in the vicinity of low-level jet,because the energy gradient force above the jet and gravity are in the opposite directions,which led that the force micelles bear equals zero in the region,so a stable structure forms.But when the micelles move to the jet exit,this balance exists no longer,the warm and humid sub-micelles move upward,and the cold and dry sub-micelles move downward,the violent weather forms.Centrifugal force formed by the earth rotation makes the light micelles produce the northward and upward movement components,which leads to the northward slope of the polar front.Cyclone is also generated by separation of the sub-micelles.When the light micelles left the micelle,they will rotate in the effect of the environment absolute vorticity field.The rotation direction is in the same direction with the initial vorticity,and geostrophic vorticity direct upward in the Northern Hemisphere,so it rotates counterclockwise and clockwise in the Southern Hemisphere.In the process of cyclone formation,light sub-micelles move along spiral path under the action of the pressure gradient force and the absolute vorticity force field,it is the reason.that common cyclone system presents with a spiral cloud and rain belt.Water vapor is the basic energy source of the cyclone in the process of the formation and strengthening.because of differences in occurrence location,there is difference in water vapor transport method between the extratropical cyclones a

关 键 词：锋面 气旋 亚微团 急流 水汽输送 台风运动 

分 类 号：P433[天文地球—大气科学及气象学]